Magnetic thread brake

ABSTRACT

Magnetic thread brake for yarn or thread feeding mechanisms. A peripherally grooved wheel is mounted for relative axial motion with respect to a braking surface and magnetic means are provided for constantly urging said wheel and braking surface together, whereby free rotation of said wheel is inhibited. Thread or yarn is fed to and wrapped around said wheel so that longitudinal movement of said yarn or thread tending to rotate said wheel is likewise inhibited and yarn drawn off from said wheel is thereby held taut. In a preferred embodiment there is also provided a preliminary braking unit immediately ahead of said wheel which tends to restrict at least lightly the passage of thread or yarn to said wheel whereby to maintain at least a slight tension on said thread or yarn as it is fed to said wheel and which will hold same firmly against further feeding if tension on the intraveling thread or yarn disappears such as by a breakage therein.

United States Patent [191 Rosen 1 MAGNETIC THREAD BRAKE Karl Isac Joel Rosen, Villa Haga, 5-52300 Ulricehamn, Sweden [76] Inventor:

[30] Foreign Application Priority Data Jan. 3, 1972 Germany N 2200058 [52] U.S. Cl. 242/155 M; 242/1521 [51] Int. Cl B6511 59/16; B65h 59/24 [58] Field of Search H 242/155 M. 152.]

[56] References Cited UNITED STATES PATENTS 2,222,921 11/1940 Van Den Bergh 242/1521 X 2,677,511 5/1954 Bley r i 242/1521 X 2.768.796 10/1956 Levineuu 242/155 M 2,924,397 2/1960 Heppner l 242/155 M 2,978,203 4/1961 Westall et a1. 242/155 M 3,352.511 11/1967 Wiggins i 242/155 M 3,753,535 8/1973 Zollinger H 242/1521 1 1 Aug. 5, 1975 Primary E.raminer-Stanley N Gilreath Attorney, Agent, or Fz'rmWoodhams, Blanchard and Flynn [57] ABSTRACT Magnetic thread brake for yarn or thread feeding mechanisms. A peripherally grooved wheel is mounted for relative axial motion with respect to a braking surface and magnetic means are provided for constantly urging said wheel and braking surface together, whereby free rotation of said wheel is inhibited. Thread or yarn is fed to and wrapped around said wheel so that longitudinal movement of said yarn or thread tending to rotate said wheel is likewise inhibited and yarn drawn off from said wheel is thereby held taut. In a preferred embodiment there is also pro vided a preliminary braking unit immediately ahead of said wheel which tends to restrict at least lightly the passage of thread or yarn to said wheel whereby to maintain at least a slight tension on said thread or yarn as it is fed to said wheel and which will hold same firmly against further feeding if tension on the intraveling thread or yarn disappears such as by a breakage therein.

8 Claims, 4 Drawing Figures PATENTEU 5975 897. 916

SHEET 1 PATENTEUMIB 5W5 SHEET FIG.3

PATEN EW 5% 3.897. 916

SHEET 4 FIG. 4

MAGNETIC THREAD BRAKE This invention relates to a magnetic thread brake comprising a thread guide roller which is journaled at one end of an axle and about which is wound a thread at least in part, and a stationary brake-magnet system, which brakes the rotation of the thread guide roller which is effected by the thread.

In a known magnetic thread brake (German Gebrauchsmuster 1,935,993) the thread to be braked en compasses at least in part two adhering discs which lie very close to each other. These thread guide discs are mechanically connected to a braking roller which is rotatably journaled in the magnetic field of an adjustable electromagnet and is coupled magnetically with the same. Such a thread brake is complex in construction and therefore involves high manufacturing costs. Furthermore, there is a danger of this assembly being susceptible to breakdowns, especially if the fine ravelings and fibers are taken into account which are present during every textile processing operation.

The object of the invention is to provide a thread brake of the class above mentioned such that it permits perfect thread tension control even at low tension and operates reliably although being of simple construc tion.

This object is accomplished in accordance with the invention by magnetizing at least in part the thread guide roller and providing a permanent magnet later ally disposed adjacent on its circumference and by journalling the thread guide roller on said axle so as to be axially slidable for urging its side surface against a stationary friction surface by means of the permanent magnet.

The thread brake in accordance with the invention is of simple construction. It has only one part which continuously rotates during operation, namely the thread guide roller. It has also been found that the braking ac tion is substantially independent of the relation of the thread to the friction surface. It is not very susceptible to breakdowns for this reason and is not affected by fine ravelings, fibers or dust. The permanent magnet has a magnetic field of a constant strength and is independent of an energy source. For this reason, it is also free from those disadvantages and disturbances which are associated with electromagnets. The thread guide roll is fixed on the axle and can be easily interchanged with another.

In order to be able to adjust the braking action of the thread brake in an easy manner, the invention provides that the permanent magnet is of cylindrical shape and is encompassed by a coil spring firmly surrounding it and that the permanent magnet together with the coil spring can be screwed into a threaded bore. In this manner, merely varying the distance between the permanent magnet and the friction surface or the thread guide roller makes it possible to vary the braking action. It is also possible to employ commercial round bar magnets and coil springs.

The thread brake is advantageous designed such that the thread guide roller is coated on the side facing toward the magnet with a material which increases the coefficient of friction or is provided with an interchangeable coating.

By suitably selecting the friction pairs, it is possible to vary the braking action step-by-step in wide ranges or to infinitely vary it when taken with the adjustable permanent magnets.

e Wm as In order to prevent the thread from slipping on the thread guide roller, it is desirable that there be provided as a preliminary brake a chamber through which the thread is conducted after passing through an entrance and outlet opening, and a sphere which is loosely disposed in the chamber and which is continuously urged into seating condition on a sphere seat surrounding the entrance or outlet aperture.

Furthermore, it is also desirable if the thread brake and the preliminary brake are secured to a common support and if the support comprises a rectangular base plate and two brackets arranged thereupon, both brackets being located on the same side of said base plate and forming a right angle between themselves and with respect to the base plate and if the the first bracket is provided as a mounting for the preliminary brake and the second bracket is provided as a mounting for the brake-magnet system, for the axle and for the friction surface. Both the preliminary brake as well as the thread guide brake are mounted on the support and thus are fixed in their positions relative to each other.

The thread brake is preferably provided with a thread guide hook on the support in the angle between the base plate and the first bracket. This hook prevents the thread passing to the thread guide roller from coming into contact with the thread issuing from the roller.

An embodiment of the invention is shown in the drawing, in which:

FIG. 1 is a side elevation of a thread brake in accordance with the invention,

FIG. 2 is the front elevation of the thread brake in accordance with the invention shown in FIG. 1,

FIG. 3 is a side elevation of the thread brake shown in FIG. I, the preliminary brake in accordance with line Ill-III in FIG. 2 being shown in section and the thread guide roller being indicated by the dotted lines and FIG. 4 is a detailed sectional elevation of the thread brake in accordance with line IV-IV in FIG. I.

The magnetic thread brake l in accordance with the invention which is illustrated in the drawing has a thread guide roller 3 about which is wound at least partially the thread 2. As can be seen from FIG. 4, this is rotatably and loosely journaled on an axle 4 and abuts with one side on a friction brake plate 5. A cylindrical or round bar, permanent magnet 6 is arranged perpendicular to this friction plate 5. It is firmly surrounded by a coil spring 7. Both the round bar magnet and the coil spring are together screwed into a threaded hole 8. The hole 8 is formed in a sleeve 9 which is fixed to the brake plate 5. The cylindrical bar magnet 6 is lacquered on its surface in order to provide a rough surface for preventing the coil spring 7 from slipping or sliding. The sleeve 9 containing the bore 8 (FIG. 4) has two cylinders 11 and 12 in its external shape which are separated by an annular circumferential recess I0. Cylinder 12 has a somewhat larger diameter and, further, it has a small cylindrical projection 13 into which the axle is inserted. The axle 4 is located in the center of the circular friction plate 5.

A support 14 has a base plate 15 and two brackets 16 and 17 which are arranged on one side of the base plate and form a right angle both relative to one another as well as relative to the base plate. The one bracket 16 serves as a mounting support for a preliminary brake l8. Bracket 17, on the other hand, has a hole 19 perpendicular to its surface and a small semicircular recess 20 at the edge of this hole. The sleeve 9 together with the cylindrical member 11 and the cylindrical projection 13 match this hole and the recess whereby the sleeve can be slid into the hole up to the recess 10. The bracket 16 also possesses a hole 21 into which the preliminary brake 18 is inserted.

The preliminary brake 18 has a chamber 22, an entrance opening 23 and an outlet opening 24. A sphere 25 which is movably disposed in the chamber 22 is urged onto a seat 26 surrounding the outlet opening 24 by the force of gravity. The housing of the preliminary brake 18 is provided with two parts, the line of separation 27 passing through the chamber. On the outside, it is designed as a cone opening at the bottom. However. as can be clearly seen from FIG. 3, the part 28 of the cylinder surrounding the outlet opening 24 is re ceived in the bore 21 of bracket 16.

A thread guide hook 30 is positioned by its shank in an angle 29 between the base plate and the tab 16, with the head 30a of said shank lying against the angle 29, and its tip extends into a recess 31 of the angle 29. The preliminary brake 18, the support 14, the sleeve 9 and the friction surface 5 are all produced of plastic. The sphere is of iron or steel. The thread guide roller consists of two magnetizable soft iron discs 33 and 34 joined by a plastic rivet 32. The two discs 33 and 34 lie back-to-back and form a guide groove 35 between themselves. The plastic rivet 32 simultaneously serves as a bearing sleeve, by means of which the thread guide roller 3 is journaled on the axle 4. The thread guide book consists of a wear-resistant material, for example. sintered ceramic.

The operation proceeds as follows by virtue of the design of the thread brake:

The thread 2 is conducted through the preliminary brake 18, is wound around the thread guide roller 3 almost completely, and lies in the guide groove 35. It issues from the thread guide roller 3 and is conducted about the thread guide hook 30. The thread 2 is drawn downwardly from the thread guide hook 30 by some kind of force. Several processes occur simultaneously during this operation. The thread 2, which is now taut, displaces the sphere 25 from its seat 26. The sphere executes irregular movements in the chamber, often coming into contact with the thread and attempting to re turn to the sphere seat under the influence of gravity. The thread is decelerated very slightly by this constant jamming or contacting action. It thus lies deep in the guide groove of the thread guide roller 3 and causes the thread guide roller to move in the direction of the thread due to the friction which is generated. The permanent magnet 6 draws the thread guide roller 3, which consists in part at least of soft iron, onto the friction plate 5. In so doing, the side of the thread guide roller 3 facing the magnet lies in direct contact with the friction plate 5, thereby producing frictional forces during rotation of the thread guide roller 3. This friction drags against the movement of the thread guide roller 3 and also that of the thread 2 as well. This brak' ing action can be easily adjusted by screwing the permanent magnet into or out of the bore 8. The support [4 can be mounted by means of screws and the holes 36 and 37 provided for this purpose.

The thread is threaded in a simple manner. The upper housing part of the preliminary brake 18 is removed and the thread is introduced through the entrance opening 23 thence through the chamber, past the sphere 25 and out through the outlet opening 24.

As can be seen from FIG. 3, the thread is passed about the thread guide roller in clockwise direction and then through the thread guide book 30. The upper housing of the preliminary brake 18 is then replaced on the lower part.

The invention is not restricted to the embodiment illustrated. For instance, it is feasible to design the thread guide roller symmetrically and to construct the two side surfaces of the soft iron discs 33 and 34 with varying degrees of roughness so that different degrees of braking action can be achieved merely by reversing the thread guide roller. Furthermore, it is also feasible to coat the sides of the thread guide roller in order to reduce either the amount of wear or to vary the coefficient of friction.

What is claimed is:

l. A magnetic thread brake comprising a thread guide roller which is adapted for receiving thread wrapped therearound and which is at least in part of magnetizable material, means rotatably mounting said roller for rotation about its axis, a rotatably fixed braking plate positioned adjacent and axially movable relative to said roller, a permanent magnet of circular cross section positioned radially offset from said axis and with one pole thereof adjacent said roller, a coil spring firmly connected to and surrounding the magnet, an im ternally threaded sleeve fixed to said brake plate and coaxially receiving said magnet surrounded by the coil spring for adjustment axially of said roller and axially of said sleeve, whereby such adjustment will vary the force by which the roller and braking plate are urged together and thereby vary the drag imposed on the thread by said roller.

2. A thread brake according to claim 1, wherein the permanent magnet is lacquered on its outer surface which is contacted by the coil spring.

3. A thread brake according to claim I, wherein the thread guide roller has on the side thereof facing the magnet a material which increases the coefficient of friction.

4. A thread brake according to claim 1, wherein the roller moves axially against the braking plate and the braking plate is fixed with respect to the magnet in at least any given adjustment thereof.

5. A thread brake according to claim 1, wherein the braking plate is axially fixed and (a) the roller is axially movable in response to the magnet and (b) the magnet is axially adjustable.

6. A thread brake according to claim 1, wherein said brake plate comprises a circular plate positioned adjacent one axial end of and substantially coaxially aligned with said roller, said sleeve being fixed to said brake plate and projecting axially therefrom in a direction away from said roller whereby said brake plate is positioned between said roller and said sleeve, said sleeve having a threaded opening extending axially there through and open at both ends, said opening being radially offset from but substantially parallel to the rotational axis of said roller, the opening in said sleeve opening through said brake plate whereby the magnet positioned within said opening has one end thereof disposed directly opposite the adjacent axial face of said roller, and said magnet having the end thereof remote from said roller projecting outwardly beyond said sleeve so that said magnet can be rotated relative to said sleeve to axially adjust said magnet relative to said roller.

further brake device for preventing slipping of the thread as supplied to said roller, said brake device including wall means defining a chamber having inlet and outlet openings through which a thread can be passed and a sphere loosely disposed in the chamber and continuously urged into engagement with a seat surrounding one of said inlet and outlet openings, said outlet opening being substantially aligned with the groove formed in said roller.

* I. II i l 

1. A magnetic thread brake comprising a thread guide roller which is adapted for receiving thread wrapped therearound and which is at least in part of magnetizable material, means rotatably mounting said roller for rotation about its axis, a rotatably fixed braking plate positioned adjacent and axially movable relative to said roller, a permanent magnet of circular cross section positioned radially offset from said axis and with one pole thereof adjacent said roller, a coil spring firmly connected to and surrounding the magnet, an internally threaded sleeve fixed to said brake plate and coaxially receiving said magnet surrounded by the coil spring for adjustment axially of said roller and axially of said sleeve, whereby such adjustment will vary the force by which the roller and braking plate are urged together and thereby vary the drag imposed on the thread by said roller.
 2. A thread brake according to claim 1, wherein the permanent magnet is lacquered on its outer surface which is contacted by the coil spring.
 3. A thread brake according to claim 1, wherein the thread guide roller has on the side thereof facing the magnet a material which increases the coefficient of friction.
 4. A thread brake according to claim 1, wherein the roller moves axially against the braking plate and the braking plate is fixed with respect to the magnet in at least any given adjustment thereof.
 5. A thread brake according to claim 1, wherein the braking plate is axially fixed and (a) the roller is axially movable in response to the magnet and (b) the magnet is axially adjustable.
 6. A thread brake according to claim 1, wherein said brake plate comprises a circular plate positioned adjacent one axial end of and substantially coaxially aligned with said roller, said sleeve being fixed to said brake plate and projecting axially therefrom in a direction away from said roller whereby said brake plate is positioned between said roller and said sleeve, said sleeve having a threaded opening extending axially therethrough and open at both ends, said opening being radially offset from but substantially parallel to the rotational axis of said roller, the opening in said sleeve opening through said brake plate whereby the magnet positioned within said opening has one end thereof disposed directly opposite the adjacent axial face of said roller, and said magnet having the end thereof remote from said roller projecting outwardly beyond said sleeve so that said magnet can be rotated relative to said sleeve to axially adjust said magnet relative to said roller.
 7. A thread brake according to claim 6, wherein said roller includes a pair of platelike discs constructed of soft iron and positioned in opposed relationship to one another and fixedly connected together so as to define a thread groove, and said means rotatably mounting said roller including shaft means extending between said brake plate and said roller, said shaft means being fixedly connected to one of said roller and brake plate and rotatable relative to the other of said roller and brake plate.
 8. A thread brake according to claim 6, including a further brake device for preventing slipping of the thread as supplied to said roller, said brake Device including wall means defining a chamber having inlet and outlet openings through which a thread can be passed and a sphere loosely disposed in the chamber and continuously urged into engagement with a seat surrounding one of said inlet and outlet openings, said outlet opening being substantially aligned with the groove formed in said roller. 